Mixed ionic-electronic conductivity in phases in the praseodymium oxide system

The praseodymium oxide system contains a series of related phases with very narrow compositional width and unique extended defect structures, rather than the more common isolated point defects. The electrical conductivity of three of these phases has been measured by the use of AC complex impedance and DC methods in the temperature range 75–400 °C. The beta phase, Pr₆O₁₁, exhibits a total conductivity of 6.77×10^–2 S/cm at 400 °C, with an activation energy of 0.52 eV/atom. The conductivity of the epsilon phase, Pr₅O₉, is slightly lower, with an activation energy of 0.51 eV/atom. The iota phase, Pr₇O₁₂, has a very low conductivity. The activation energies for electrical transport in the beta and epsilon phases are in the general range found in a number of mixed conductors based upon LSGM oxides. Electronic Publication     

含NS和NNSS供电子原子的钌(Ⅱ)羰基配合物

通过[RuHCl(CO)(PPh₃)₂(B)] (B=PPh₃, 吡啶 (py), 哌啶 (pip), 吗啉 (morph))与适当的席夫碱按1∶1的物质的量的比反应，合成了二齿和四齿席夫碱钌(Ⅱ)配合物。所用席夫碱配体通过S-苄基二硫代肼基甲酸酯与2,3-丁二酮(物质的量的比分别为1∶1和1∶2)的缩合反应制得。通过元素分析和多种物理化学方法对钌(Ⅱ)配合物和其席夫碱配体进行了表征。钌(Ⅱ)配合物为六配位的反磁性物质。用三种细菌对席夫碱配体及其钌(Ⅱ)配合物的抗微生物活性进行了筛选试验。     

Antibacterial and luminescent properties of new donor–acceptor ruthenium triphenylphosphine–bipyridinium complexes

The known compounds N-(2,4-dinitrophenyl)-4,4′-bipyridinium (2,4-DNPhQ⁺), N-phenyl-4,4′-bipyridinium (PhQ⁺) and N-(4-acetylphenyl)-4,4′-bipyridinium (4-AcPhQ⁺) have been used to prepare a series of ruthenium complexes of the type [RuCl(CO)(PPh₃)₂(L)] (where, L = 2,4-DNPhQ⁺ or PhQ⁺ or 4-AcPhQ⁺). The latter complexes reacted with sulphur derivative to give [RuCl(CO)(PPh₃)₂(L)(L′)] (where, L′ = thio-9-xanthone). These new ruthenium complexes display intense, visible metal-to-ligand charge-transfer (MLCT) absorptions, due to dπ(Ru) → π*(pyridinium) excitations. The MLCT energy decreases as the acceptor strength increases in the order PhQ⁺ < 4-AcPhQ⁺ < 2,4-DNPhQ⁺. The new ruthenium complexes have been characterized by using standard analytical and spectroscopic techniques. Fluorescence and antibacterial activity of the ligands and appropriate complexes has also been carried out.     

New ruthenium(III) complexes containing tetradentate Schiff bases and their antibacterial activity

Ruthenium(III) complexes, [RuX(EPh₃)(LL)] (X = Cl, Br; E = P, As; LL-acactet, dbm-tet, dbm-o-ph), have been synthesised by reacting [RuCl₃(PPh₃)₃], [RuCl₃(AsPh₃)₃], [RuBr₃(AsPh₃)₃] or [RuBr₃(PPh₃)₂(MeOH)] with tetradentate Schiff bases such as bis(acetylacetone)tetramethylenediimine (H₂acactet), bis(dibenzoylmethane)tetramethylenediimine (H₂dbmtet) and bis(dibenzoylmethane)-o-phenylenediimine (H₂dbm-o-ph). All the complexes have been characterised by elemental analysis, i.r., electronic spectra, e.p.r., magnetic moment and cyclic voltammetric data and an octahedral structure has been tentatively proposed. These new complexes have been tested for their antibacterial activities.     

Effect of B-site substitution of (Li,La)TiO3 perovskites by di-, tri-, tetra- and hexavalent metal ions on the lithium ion conductivity

We report the synthesis and lithium ion conductivity of di-, tri-, tetra- and hexavalent metal ion B-site substituted (Li,La)TiO₃(LLT) perovskites. All 5–10 mol% Mg, Al, Mn, Ge, Ru and W ion substituted LLTs crystallize in a simple cubic or tetragonal perovskite structure. Among the oxides investigated, the Al-substituted perovskite La_0.55Li_0.36□_0.09Ti_0.995Al_0.005O₃ (□=vacancy) exhibits the highest lithium ion conductivity of 1.1 × 10⁻³ S/cm at room temperature which is slightly higher than that of the undoped (Li,La)TiO₃ perovskite (8.9 × 10⁻⁴ S/cm) at the same temperature. The lithium ion conductivity of substituted LLTs does not seem to depend on the concentration of the A-site ion vacancies and unit cell volume. The high ionic conductivity of Al-substituted LLT is attributed to the increase of the B(Al)-O bond and weakening of the A(Li,La)-O bond. The conductivity behavior of the doped LLT is being described on the basis of Gibbs free energy considerations.     

Ionics—a key technology for our energy and environmental needs on the rise

Ionics is a key technology for storing, converting and using energy efficiently as well as protecting the environment. Major progress has been achieved in recent years in the understanding and development of individual materials components needed for ionic devices. It should be emphasized that only combinations of materials are eventually important and at least four interfaces exist with electronic and ionic junctions. The electrical fields exist over distances in the atomic range. Examples are given of recent successful developments of practically useful solids for lithium and oxide ion conduction in combination with appropriate electrodes. In addition, recent approaches to the design of ionic devices are described, notably the SEA concept for generating voltages in fuel cells and the coloration of single phase electrochromic materials. In order to overcome the tremendous problems in developing wide spread commercial applications, it is necessary to intensify our efforts in fundamental materials research drastically.     

On the structure ofp-zero-sum free sequences and its application to a variant of Erdös-Ginzburg-Ziv theorem

Letp be any odd prime number. Letk be any positive integer such that . LetS = (a ₁,a ₂,...,a _2p−k ) be any sequence in ℤ_p such that there is no subsequence of lengthp of S whose sum is zero in ℤ_p. Then we prove that we can arrange the sequence S as follows:

Palladium nanoparticles on silica-rich substrates by spontaneous reduction at room temperature

Metallic palladium nanoparticles (<5 nm) have been spontaneously obtained from an acid solution of palladium chloride salt on silica-rich substrates (sepiolite, microfibrous silica, fumed silica, and milled silica glass) without any additional reduction treatment. Variable proportions of metallic palladium were straightforwardly obtained, depending on the nature of the substrate. The presence of a large amount of silanol groups acting as nucleation centers, seem to be a requisite to obtain small Pd nanoparticles. Additionally, an absorbance maximum associated to a surface plasmon resonance corresponding to the spherical particles of metallic palladium has been identified at a wavelength of 238 nm. The large specific surface of the employed substrates with the palladium nanoparticles suggest that these materials could be used for gas catalysis.